1. Field of the Invention
The present invention relates to a cleaning sheet and a recording medium set including the cleaning sheet.
As known well, in an image forming apparatus such as a printer, a facsimile or the like, a sheet-shaped recording medium supplied thereto is delivered by use of delivery means, images are formed on the recording medium, and the recording medium with the images formed thereon is then discharged therefrom. When images are formed on a number of recording mediums larger than a preset number of recording mediums, the delivery performance of the delivery means for delivering the recording mediums may be degraded. That is, more particularly, the present invention relates to a cleaning sheet, which is supplied to the image forming apparatus in place of the above-mentioned recording medium, and a recording medium set including the cleaning sheet to recover the degraded delivery performance upon the aforementioned situation.
2. Description of the Prior Art Generally, there is widely known an image forming apparatus such as a printer, a facsimile, or the like which is arranged to deliver a sheet-shaped recording medium supplied thereto by use of delivery means, to form images on the recording medium and then to discharge the recording medium with the images formed thereon.
The image forming apparatus of this type, normally, includes a feed roller for feeding a recording medium into the apparatus, delivery means such as a delivery roller, a delivery belt or the like for delivering the recording medium fed by the feed roller, and a discharge roller for discharging out the recording medium with the image formed thereon externally of the apparatus.
On the other hand, as the recording medium, there are known various kinds of things such as ordinary paper, coated paper, OHP (overhead projector) sheet, calendered paper, bright film and the like.
In the above-mentioned image forming apparatus, if images are formed in a larger number of recording mediums than a preset number of recording mediums, then paper powder or the like is adhered in large quantity to the feed roller, delivery means such as the delivery roller or the like, and discharge roller. This reduces the frictional force of these rollers with respect to the recording medium which, in turn, results in the degraded delivery performance of these rollers for delivering the recording medium, That is, if the delivery performance of the feed roller is degraded, then there occurs the poor feeding of the recording medium, poor head search of the recording medium and the like; if the delivery performance of the delivery roller is degraded, then there occurs the poor head search, delivery pitch shifting and the like; and, if the delivery performance of the discharge roller is degraded, then there occur the delivery pitch shifting, poor discharge of the recording medium and the like.
Especially, when the coated paper or the like (such as coated paper, OHP sheet, calendered paper, bright film, or the like; this way of expression will be used hereinafter) is used as the recording medium, the delivery performance of the delivery means of the image informing apparatus is degraded after only a relatively small number of sheets is printed. Since the surface of the coated paper is flat when compared with the surface of the ordinary paper, if two or more sheets of coated paper are superimposed on top of each other, they easily adhere to each other. On the other hand, most of the image is forming apparatuses include a paper feed tray which is used to hold a large number of recording mediums to be fed by the feed roller in such a manner that they are superimposed one on top of another. That is, if a large number of sheets of coated paper are set in a superimposed manner in the paper feed tray, then there is a fear that there can occur a multiple feeding (two or more sheets of recording medium can be fed together). Therefore, generally, a gap agent (for example, particles of the order of 10.mu.)) is mixed into a coated layer of the coated paper in order to prevent this coated paper from adhering to the coated paper that is just superimposed on top of this coated paper. Alternatively a lubricant is coated on the back surface of the coated paper in order to enhance the slidability of the coated paper with respect to the coated paper that is superimposed on bottom of this coated paper.
The above-mentioned gap agent or lubricant, in a process in which the coated paper or the like is delivered, is peeled off from the coated paper or the like and adheres to the rollers and the like of the image forming apparatus, so that the delivery performance of the rollers and the like for delivering the recording medium is lowered greatly when compared with the paper powder.
That is, when the coated paper or the like is used as the recording medium, the delivery performance of the delivery rollers and the like is degraded with a relatively small number of recording mediums delivered.
As means for solving the above-mentioned problems, conventionally, there is known a cleaning sheet which is disclosed in Japanese Utility Model Pulication No. Hei. 5-18835.
As shown in FIG. 9, in the cleaning sheet S, at least on one surface of the upper and lower surfaces of a sheet member 1, there is (are) formed an adhesive layer (adhesive layers) 2 and the surface(s) of the adhesive layer(s) 2 is (are) covered with a fiber layer (layers) 3 (for example, unwoven cloth layer).
According to this cleaning sheet, when the recording medium delivery performance of the image forming apparatus is degraded, if the cleaning sheet is supplied instead of the recording medium, then the paper powder, gap agent, lubricant and the like stuck to the delivery means of the image forming apparatus are adsorbed to the adhesive layer(s) 2 through the fiber layer(s) 3, which makes it possible to recover the degraded delivery performance of the image forming apparatus.
However, in the above-mentioned conventional cleaning sheet, since the surface of the adhesive layer 2 is covered with the fiber layer 3, when the present cleaning sheet is supplied to the image forming apparatus instead of the recording medium, there is a fear that the fiber per se which forms the fiber layer 3 can adhere to the delivery means of the image forming apparatus, so that the delivery performance of the image forming apparatus cannot be always recovered effectively.
Also, in the above-mentioned conventional cleaning sheet, because the adhesive layer 2 formed of a tacky agent is provided on the whole of at least one surface of the sheet member 1, in an image forming apparatus of a type including a feed roller which is contactable with the upper surface of a recording medium to supply the recording medium by means of its frictional force produced with respect to the recording medium, if the cleaning sheet is set in such a manner that the adhesive layer 2 and paper feed tray are opposed to each other, then there is a fear that a frictional force between the cleaning sheet and paper feed tray while the feed roller is in operation can increase to thereby fail to supply the cleaning sheet.